Cyclic ethers are polymerized by various means to give products of widespread utility. For instance, ethylene oxide is polymerized to polyethylene oxide which is useful, in lower molecular weight grades, for ceramics (as a binder), cosmetics, lubricants, polyurethanes; and in higher molecular weight grades, for packaging film, denture adhesives, lubricants, flocculation and for other articles and products. Tetrahydrofuran (THF) is polymerized to poly(tetramethylene ether)glycol which is useful in the preparation of Spandex fibers; polyurethane resins which are useful in elastomeric parts; and thermoplastic elastomers which are useful for molding various mechanical parts. Therefore, improved methods of making these polymers are sought. Also useful are methods of depolymerizing the polyethers to useful products, such as the cyclic ethers from which they were originally made. Such depolymerizations allow for the recycle of off specification or used polyethers to useful products such as polyethers, thereby reducing waste.
Block copolymers, of polytetrahydrofurans (usually as the diols) and polyesters or poly(urea-urethanes) are commonly used in commercial products, such as thermoplastic elastomers (Hytrel.RTM. thermoplastic elastomer), spandex fibers (Lycra.RTM. spandex fiber) and urethane rubbers (Adiprene.RTM. Urethane rubber). The usual procedure in making these products is to combine a polyether diol with suitable reactants, such as ester segment forming compounds, or urea and/or urethane forming compounds such as amines and/or diols with diisocyanates. Improved methods of making such commercially important polymers are sought by the artisan.
U.S. Pat. No. 3,842,019 describes the polymerization of oxiranes and other small ring compounds by a presumed cationic mechanism, using as the catalyst the decomposition products of metal perfluoroalkylsulfonates. These catalysts are described as "latent", that is no reaction occurs until the metal salt is decomposed. The reactions reported are relatively slow, even at elevated temperatures.
U.S. Pat. Nos. 5,084,586 and 5,124,417 describe the cationic polymerization of various monomers, including cyclic ethers, using onium cations, whose corresponding anions are fluoroalkylsulfatometallates. Onium ion catalyzed cationic polymerizations are well known, and there is no mention in these patents of the use of metal salts not containing onium ions, such as metal triflates, as catalysts for the polymerization of cyclic ethers.
Japanese Patent Application 51-82397 describes the polymerization of tetrahydrofuran using a combination of fluorosulfonic acid and a carboxylic acid as catalysts. No mention is made of metal salts, such a metal triflates as catalysts.
J. S. Hrkach, et al., Macromolecules, vol. 23, p. 4042-4046 (1990) describe the polymerization of tetrahydrofuran using trimethylsilyl trifluoromethanesulfonate as the initiator. No mention is made of any other triflates as catalysts for this polymerization.
German Patent Application 2,459,163 describes the polymerization of THF using a combination of ferric chloride and carboxylic anhydride as catalyst.
G. A. Olah, et al., J. Appl. Polym. Sci., Vol. 45, 1355-1360 (1992) describe the use of boron, aluminum and gallium tristriflate to catalyze the polymerization of THF.
S. L. Borkowsky, et al., Organometal., Vol. 10, p. 1268-1274 (1991) report that certain zirconium complexes can initiate the polymerization of tetrahydrofuran. No mention is made of zirconium perfluoroalkylsulfonates, or of copolymers.
T. Misaki, et al., Nippon Kagaku Kaishi, p. 168-174 (1973) report on the polymerization of THF using a combination of metal aceylacetonates and acetyl chloride.
U.S. Pat. No. 4,303,782 describes the use of zeolites to catalyze the polymerization of tetrahydrofuran. These polymerization appear to proceed very slowly.